1. Field of the Invention
This invention relates to a method and an apparatus for manufacturing composite steel ingots, and more particularly to a method and an apparatus suitable for filling metals in the empty portion of a hollow steel ingot or the outer peripheral portion of a steel ingot through electroslag remelting thereby to form a composite steel ingot.
This invention is applicable to rolls for rolling and rollers for guiding rolled materials both of which are used in rolling facilities, rollers for guiding steel ingots used in continuous casting machines, rotor shafts for generators, and other shafts for various uses.
2. Description of the Prior Art
It is disclosed in Japanese Patent Laid Open No. 57-36087 to rotate a cylndrical steel ingot, when carrying out pad welding on the cylindrical steel ingot by the use of an electroslag welding method which has the same principle as that of an electroslag remelting method. In this method, a plurality of consumable electrodes are employed and an electric current is taken out from one point of the steel ingot. A problem which occurs with the known method is that the density of melting current becomes nonuniform. In the embodiment disclosed in the above Laid Open Patent, the cylindrical steel ingot is rotated at a constant speed of 1 rpm during the process of welding.